We propose to extend our original observation of a hitherto unknown material isolated from the bovine pineal gland which will inhibit ovulation. This was found to be effective in blocking the effects of endogenous secretion of gonadotropin. To this end we shall prepare larger quantities and submit the extracts to further purification after which the nature of the active compound will be elucidated by modern methods including mass spectrometry. We propose to investigate further the biological activity of the compound using the following experiments: (1) Using radioimmunoassays for rat FSH and LH, we will determine if administration of the compound produces a lowering of these hormones in the intact animal. (2) Evaluation of the suppression of endogenous secreted gonadotropin by following inhibition of ovulation both directly, as shown by the absence of ova in the oviducts, and indirectly through observing blocking in fertility after copulation.